The Lipid and Lipoprotein Biochemistry Core Laboratory will serve all projects on a highly interactive basis. The projects propose diet experiments that will produce more than 2,000 blood samples during each year of the grant period. This Core Unit will acquire these blood samples and prepare the serum, plasma, and DNA from the buffy coats. Samples will be inventoried, aliquotted, maintained at -80 degrees C, and made available to program investigators for determination of various cardiovascular disease-related phenotypes. Some of these determinations will be made within Core Unit A and are listed below. Standard clinical chemical procedures will be used to quantify serum TSC and HDL-C (after precipitation) and, by subtraction, VLDL+LDL-C concentrations. We will continue our long-standing participation in an external quality assurance program to ensure the accuracy of these measurements. ApoAI, apoB and apoE concentrations will be assayed using turbidometric approaches with commercially-available reagents, and Lp(a) concentrations will be assayed using a 'sandwich'-style ELISA, also commercially available. These assays are already being used in this program. Nondenaturing gradient gel electrophoresis will be used to assess cholesterol distributions among sizeresolved lipoproteins using composite gradient gels that enable evaluation of both LDL and HDL phenotypes in the same gel lane. We will determine fractional absorbance in four fractions of HDL (HDLl1a, HDL1b, HDLz, HDL3) and in six fractions of beta-lipoproteins, including four fractions ofLDL (LDL1, LDL2, LDL3, and LDL4) and two fractions of larger lipoproteins (VLDL and IDL). Finally, Core Unit A will be responsible for placing lipid and lipoprotein phenotype data and inventory information on stored blood samples into computerized data files (via Core Unit B) and making them available to all program investigators.